Browsing by Subject "geometry"

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  • von Plato, Jan (2018)
    Brouwer introduced in 1924 the notion of an apartness relation for real numbers, with the idea that whenever it holds, a finite computation verifies it in contrast to equality. The idea was followed in Heyting's axiomatization of intuitionistic projective geometry. Brouwer in turn worked out an intuitionistic theory of "virtual order." It is shown that Brouwer's proof of the equivalence of virtual and maximal order goes only in one direction, and that Heyting's axiomatization needs to be made a bit stronger. (C) 2018 Published by Elsevier B.V. on behalf of Royal Dutch Mathematical Society (KWG).
  • Jimenez, Jose Beltran; Heisenberg, Lavinia; Koivisto, Tomi (2020)
    The geometrical formulation of gravity is not unique and can be set up in a variety of spacetimes. Even though the gravitational sector enjoys this freedom of different geometrical interpretations, consistent matter couplings have to be assured for a steady foundation of gravity. In generalised geometries, further ambiguities arise in the matter couplings unless the minimal coupling principle (MCP) is adopted that is compatible with the principles of relativity, universality and inertia. In this work, MCP is applied to all standard model gauge fields and matter fields in a completely general (linear) affine geometry. This is also discussed from an effective field theory perspective. It is found that the presence of torsion generically leads to theoretical problems. However, symmetric teleparallelism, wherein the affine geometry is integrable and torsion-free, is consistent with MCP. The generalised Bianchi identity is derived and shown to determine the dynamics of the connection in a unified fashion. Also, the parallel transport with respect to a teleparallel connection is shown to be free of second clock effects.